$\frac{dp}{dt}=3\left(20-p\right)$

$\left(a+b\right)^2+19\left(a+b\right)+60$

$\lim_{y\to2\pi}\left(\frac{\sin\left(6y\right)}{\sin\left(3y\right)}\right)$

$\frac{4^9}{4^3}$

$\lim_{n\to\infty}\left(\frac{n+2}{x^2-4}\right)$

$\left(4x+1\right)\cdot\left(4x-1\right)$

$xdx=tdt$